摘要
当前土壤重(类)金属污染导致的农作物重(类)金属超标已成为我国居民严重关切的问题之一。在重(类)金属胁迫下,植物自身具备了相应的机制来减少其对重(类)金属的吸收富集,这些机制主要与土壤-植物根系系统中发生的一些物理、化学和生物学过程有关。本综述阐述了与植物根系相关的限制重(类)金属吸收/转运因素及其机制,主要包括:1)根系的一些分泌物能通过与重金属螯合降低其有效性,从而达到固定重金属的目的;2)在重(类)金属胁迫下,植物根系增加粗根比例,降低细根数量并减少根比表面积,从而降低与重(类)金属接触的几率并影响重(类)金属的吸收;3)水生植物根系表面形成氧化铁/锰化合物胶体,这些胶体能吸附阴阳离子,从而束缚重(类)金属;4)植物根系表面具有相应的吸附位点,具有相似性质的离子会对这些位点产生竞争,从而降低重(类)金属进入根系细胞的几率;5)细胞壁组分含有的基团可与重金属结合,从而束缚大量的重金属;6)植物根系内皮层凯氏带能阻断重(类)金属在皮层与维管柱之间的质外体运输,从而阻止重(类)金属向地上部分转运;7)具有相似性质的金属离子可对根系细胞膜上的离子通道展开竞争,这一过程影响重(类)金属的吸收;8)在细胞中游离的重(类)金属可被区隔到根系液泡中,从而减少其毒性以及向地上部分的转运;9)根系细胞膜上的一些基因的表达限制了重金属由根系向地上部分的转运。综上所述,植物主要通过减少根系与重(类)金属接触几率、吸附机制、离子竞争性吸收、以及区隔化作用等机制来降低重(类)金属的吸收和转运。但关于细胞壁组分在束缚阴离子形态存在类金属的相关机制还不清楚,尚待进一步明晰和阐明。
Heavy metal(metalloid)pollution in soils has caused excessive accumulation of them in crops,which has become one of the serious concerns of residents in the vicinity of some polluted regions in China.Plants have developed many mechanisms,by which,to restrict the uptake,translocation and enrichment of heavy metals(metalloids)in plants.The above mechanisms are mainly related to the physical,chemical and biological processes occurring in the plant root-soil system.This review attempts to summary the mechanisms equipped by plant root system on affecting the uptake,translocation and toxicity of heavy metals(metalloids)in plants.The main mechanisms include:1)plant roots will secrete some exudates which can bind with heavy metals so as to stabilize heavy metals;2)plants will alter their root morphology,such as enhancing coarse root ratio,and reducing fine root numbers and root surface,in response to the exposure of heavy metals(metalloids)to reduce their uptake by plants;3)root iron plaques(amphoteric colloid,mainly containing iron and manganese oxides)will be formed on the root surface of aquatic plants,which can adsorb cations and anions so that sequestrate heavy metals(metalloids);4)the competition adsorption between ions with similar physicochemical properties will occur on the surface of plant roots for the same adsorbing sited on the root surface,wich can reduce the entrance probability of heavy metals into the inner cells;5)plant cell wall contain some function groups,acting as a barrier and/or an adsorption layer in restraining the transfer of heavy metals(metalloids);6)Casparian band in plant root endodermis can act as a barrier to block the transport of heavy metals(metalloids)between the cortex and vascular column,thus preventing their transport to the ground part;7)metal ions with similar properties will compete with ion channels in root cell membranes,and this process affects their absorption by plants;8)heavy metals(metalloids)that float in cells can be sequestered into root vacuoles,thereby reducing their
作者
刘梓清
杨继刚
吴子涵
李增飞
宋变兰
冯人伟
LIU Zi-qing;YANG Ji-gang;WU Zi-han;LI Zeng-fei;SONG Bian-lan;FENG Ren-wei(Institute of Environmental Microbiology,College of Resources and Environment,Fujian Agriculture&Forestry University,Fuzhou,Fujian 350002,China;China Aerospce Academy of Architectural Design&Research Co.,Ltd 100071,China)
出处
《农业现代化研究》
CSCD
北大核心
2021年第2期284-293,共10页
Research of Agricultural Modernization
基金
国家自然科学基金面上项目(41877497)。
关键词
根系
重(类)金属
毒性
吸收与转运
细胞壁
液泡
root system
heavy metals(metalloids)
toxicity
absorption and transport
cell wall
vacuole
